The present invention relates to an apparatus for straightening a spinal column and more particularly to an apparatus which maintains a desired spatial relationship between adjacent vertebrae and the sacrum.
An article entitled "Rhamatisme Vertebra" by Roy-Camille, Sailliant and Judet discloses the use of a rigid plate to hold adjacent vertebrae and the sacrum in a desired spatial relationship. When the rigid plate is to be mounted on the spinal column, accurately located holes are drilled in the vertebrae and the sacrum. Holes in the plate are then positioned in alignment with the holes in the vertebrae and sacrum. Screws are then twisted into the vertebrae and sacrum to clamp them to the plate. The screws extend perpendicular to the plate.
Due to the relatively thin construction of the sacrum, one or more of the screws may extend through the sacrum unless the screws are very accurately positioned and the length of the screws carefully selected to be less than the thickness of the sacrum. Of course, if a screw extends through the sacrum, the body organs on the opposite side of the sacrum could be injured by the screw.
U.S. Pat. No. 4,047,523 discloses an L-shaped sacral anchor that is used to secure a cable to the sacrum in carrying out a scoliosis correction operation. One leg of the L-shaped anchor consists of two prongs which are inserted in the disc space between two sacral vetebrae. The other leg is a bridge portion that connects the two prongs and which has a collet formed integrally therewith for receiving a cable.